If you keep the rez temp between 65-68ºf then all you need to do is make sure there a lots of bubbles.
I alway throw a small aquarium powerhead in the bottom of the rez so that everything stay well circulated.
Botanicare states this about Hydroguard:
HYDROGUARD™ is a biological water treatment that helps suppress and resist damping off diseases. HYDROGUARD ™ is an all-natural biological stimulant that assists in the management of disease cycles. Unlike the use of fungicides alone, the use of HYDROGUARD ™ breaks the chronic disease cycle while leaving no toxic residues.
If you are growing new roots, then your process is working and I would keep going with it.